I just updated to the latest performance profiler and ran a fairly short profile session of some of my time sensitive code, which ended up with a 500 mb profile results file. However opening that takes ~5 minutes to load and 3 gb of memory (which sometimes seems to grow up to 10 gb before my sisten gives out). Resizing the main window or clicking anywhere freezes the application for a minute or so. Is this to be expected?

Sorry you had a problem with the Perfomance Profiler. You will get a lot of data produced when profiling using the "line-level" mode and the application will start to behave unreliably when memory use exceeds 1GB. You have simply reached its limits. You can turn down the data requirements if you, for example, select "sampling mode" which is recommended for long tests.